The paper "Current Applications of Styrenic Block Copolymers of Rubbers" by G. Holden, Journal of Elastomers and Plastics, Vol. 14, (July 1982) p. 148, teaches that styrene butadiene styrene (SBS) block polymers are compatible with polystyrene and hydrogenated styrene butadiene styrene or styrene ethylene butadiene styrene (SEBS) polymers are compatible with a wide range of engineering resins including nylon, polybutylene terephthalate (PBT), polyacetal and polycarbonate. The reference does not teach that a blend of SEBS, a polyalkylene terephthalate and a vinyl aromatic polymer is or would be useful to compatibilize laminates of high impact polystyrene (HIPS) and aromatic polyesters such as PBT or polyethylene terephthalate (PET).
There are abstracts of a number of patents which suggest laminates may be made of PBT or PET and polystyrene using as an intermediate layer a functionalized SEBS. Representative of this art is Chemical abstract 1997:243702 of Japanese Kokai 09029915 which teaches a three layered laminate comprising a layer of a poly(alkylene terephthalate), a layer of an epoxidized vinyl aromatic conjugated diene compound block copolymer and polystyrene compound. Specifically, a laminate of PET, an SB block copolymer treated with AcOOH and high impact polystyrene is used in the packaging of electronic parts. The reference does not teach the use of SEBS nor does the reference teach a compatibilizer which is a blend of SEBS, a polyalkylene terephthalate and a styrenic polymer as a compatibilizer for a laminate of a polyalkylene terephthalate and high impact polystyrene. Further the compatibilizers of the present invention are not functionalized in the sense taught by the reference.
Similarly Chemical Abstract 1996:114283 of the effect of PS-GMA as an in situ compatibilizer on the morphology and rheological properties of the immiscible PBT.PS blend, Kim, Jin Kon; Lee, Hawyong (Dep. Chemical Engineering, Pohang Univ. Science and Technol., Kyungbuk, 790-84(S. Korea) Polymer, 37(2), 305-11,1996 teaches that a functionalized polystyrene, namely polystyrene functionalized with glycidyl methacrylates is useful as an in situ compatibilizer for blends of PBT and PS. The glycidyl methacrylate reacts with the carboxylic acid group from the PBT. The reference does not teach a three-component compatibilizer of HIPS, polyalkylene terephthalate, and SEBS.
Chemical Abstract 1996:503062, compatibility enhancement and toughening of poly(butylene terephthalate(/poly(phenyleneoxide) blends using a reactive compatibilizer, Kim, Dongsup; Park, Jae-Hyung; Kim Jinhwan; Ahn, Jungho; Kim, Hyungsu; Lee, Sai-Soo (Dept. Polymer Sci.&Eng.), SungKyunKwan Univ. Kyunggi, 440-746, (S. Korea) Pollimo, 20(4), 611-621 (Korean) 1996, teaches blends of PBT/PPO, a reactive compatibilizer and SEBS. The reactive functionalilzer either had an end group such as glycidyl methacrylate which could react with the polyester (PBR) or was miscible in the PPO such as polystyrene. The reference teaches away from the present invention as it requires the presence of PPO or a functionality which reacts with the polyester, such as glycidyl methacrylate, neither of which are in the compatibilizer blends of the present invention.
Applicants have not been able to find a reference which teaches a blend of a polyalkylene terephthalate, HIPS and SEBS, optionally with additional (crystal) polystyrene as a blend per se or as a compatibilizer for a laminate of polyalkylene terephthalate and HIPS.